Apparatus for telephone-switchboards.



No. 667,46l. Patented Feb. 5,1901.-

c. 2-. scmsmzn. APPARATUS FOR TELEPHONE SWITGHBOABDS.

(Application filed Jan. 9, 1897.)

(No Model.)

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UNITED STATES ATENT Fnica CHARLES E. SCRIBNER, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE WESTERN ELECTRIC COMPANY, OF SAME PLACE.

APPARATUS FOR TELEPHONE-SWITCHBOARDS.

SPECIFICATION formingpart of Letters Patent No. 667,461, dated Februar 5, 1901.

I Application filed January 9, 1897, Serial No- 618,530. N 1110681 To all whom it may ally described as follows: A shunt is placed Be it known that I, CHARLES E. SCRIBNER, about the line signal-lamp, and a relay which a citizen of the United States, residing at Chimay be common to a considerable group of cago, in the county of Cook and State of Illilines is placed in a local circuit of the lamps, 5 nois, have invented a certain new and useful sufficiently sensitive to respond to current Improvement in Apparatus for Telephonethrough any of the shunts, and is arranged to Switchboards,(Case No. 439,) of which the folcontrol any suitable general or alarm signal. lowing is a full, clear, concise, and exact de- The circuit of the supervisory lamp is cornscription, reference being had to the accompapleted during connection with a line through to nying drawing, forminga part of this specifia circuit made up in part of the line-lamp of cation. the line, so that in the event of interruption This invention concerns the mechanism of the circuit through the line-lamp the norassociated with telephone-lines in a switchmal operation of the supervisory signal is disboard for signaling to the attendant and inturbed and the unusual appearance calls the 15 dicating the use or-disuse of the appliances operators attention to the condition of the at the stations. It concerns the use of incanline-lamp.

descent lamps as secondary signals controlled In the specific form of the invention which by suitabledevices directly responsive to sig- I am about to illustrate the cut-0E relay is naling-currents in the lines. provided with differentially-wound helices,

20 One object is to guard against the interrupwhich are serially connected and constitute tion of service by the breaking of the signalthe shunt about the line-lamp. The point of lamp of a line by indicating the interruption junction of these helices is united with a conof the circuit through the lamp to an operator tactpiece in the springjack or terminal making connection with the line. socket of the line, with which a suitable con- 2 5 A further object of the device is to provide tact of the connecting-plug registers, the conmeans for setting a general signal before any tact portion of the plug being the terminal of operator to indicate a call from any of the a conductor, including the supervisory sigsubscribers under her care or to serve as a nal, together with a source of current. A renightsignal. lay in the plug-circuit controls the super- 0 In signaling systems of the type mentioned visory signal by closing about the supervisory the line-signal is commonly placed in alocallamp a shunt having a resistance nearly battery circuit controlled by a relay responequal to that of the lamp when the relay is sive to currents in the subscribers line, such excited. The electromagnet controlling the current in the line being determined by a night-signal is a magnet of very low resist- 5 switch at the station, the position of which is ance interposed in the circuit of several linechanged duriugthe useofthe telephonethere. lamps and constructed to close a local cir- The operator is furnished with the usual concuit, including a general signal-lamp or any necti'ng-plugs for uniting lines and with other suitable alarm. Thesubscribers act of callsignals, termed supervisory signals, assoing causes the line-relay of the correspond- 9o 40 ciated with the connecting-plugs and coning line to close the local circuit through trolled by other relays in the plug-circuit the line-lamp. If this lamp be not broken, similarly responsive to currents in the lines. the line-lamp and the general signal-lamp In some instances an electromagnetic switch, controlled by the relay in the local circuit termeda cut-off relay,is arranged to break with the line lamp will light simultaneously.

45 the normal connections of the line with the If, however, the circuit through the lineline-relay which controls the line-signal, this lamp be interrupted, the general lamp alone cut-off relay being excited through current will light, which will call the attention of applied in the act of making connection with the operator to the defective condition of the the line. The present invention is designed line-lamp. Also if an operator should make I00 50 for use in connection with such a system of connection with a line called for. the supersignals. Its several features may be genervisory signal corresponding to the plug used in making the connection should become illuminated under normal circumstances, there being no current through the relay controlling the supervisory signal, and the local circuit of the signal being complete and of normal resistance through the line-lamp. In this case the interruption of the circuit through the latter lamp would be signified by the dimming of the supervisory signal at a time when it should be bright. The connection of the dilferential windings of the cut-oft relay with the special contact-pieces in the springjack, which are customarily adapted for testing in multiple switchboards, has the incidental advantage of causing the initial act of the subscriber in removing his telephone from its switch in order to procure a connection to alter the electrical condition of the test-rings, and thus to make the line-test busy.

The attached drawing is a diagram of the circuits of this invention. It represents two stat-ions connected by telephone-lines with switching and signaling mechanism in the switchboard. The apparatus at the station may be of any well-known form adapted for the automatic operation of signals, the essential condition being that a change in the electrical state of the line be produced during the use of the telephone. A suitable arrangement consists in a condenser in circuit with the bell at the station which will permit the circulation in the line of the alternating currents employed to operate the hell, but will constitute a break as to continuous currents. Then the removal of the station-telephone from its switch for use will complete the linecircuit as to battery-currents and permit the operation of a signal in the switchboard.

The line conductors 1 and 2 are led to the spring-jacks a and or, in the switchboard and are extended the one to earth and the other to the free pole of a grounded source b of current, the magnet c of the signal-controlling relay being interposed in the latter conductor 2. The lever c of the relay forms the terminal of a conductor 3, extending to the free pole of the grounded battery d. The contactanvil of the relay forms the terminal of another wire 4, extending to earth and including the line-lamp e, which is placed near the spring-jack at of the line in one of the sections of switchboard.

The continuity of the line conductors l and 2 is controlled by the switch-contacts of the cut-off relay f, which is arranged to break the connection of the line-wires with the ground and with the relay 0, respectively, when the relay f is excited. This relay is Wound with two helices f and f which are connected in series in a conductor 5, being arranged differentially as to currents circulating in that conductor. Conductor 5 is united with wire 4 in such a way as to bring it into shunt about the line-lamp e. The point of junction of the windings f and f is united by a wire 6 with test-rings g in the spring-jacks a and a.

A portion of theconductor 3 may be common to all the members of the group of lines assigned to the care of one operator. This common conductor includes the magnet of a relay h, whose switch-contacts control a local circuit including a lamp or other alarm or signal i, which may be placed before the operator.

The usual plugs and k are furnished in the switchboard for the use of the operator in uniting lines. Each plug has three contact-pieces Z, Z, and Z which make connection with the two line-springs and with the thimble g of a spring-jack into which the plug is inserted. The contact-pieces Z and Z of the two plugs of a pair are'united by conductors 7 and 8, respectively, which constitute the plug-circuit. This plug-circuit is equipped with the usual calling-key m for connecting a source of calling-current with the plug is, and listening-key n for connecting an operators telephone with the plug-circuit. The side 8 of the plug-circuit is connected to the free pole of the grounded battery b by a conductor 10, which includes the winding 0 of an impedance-coil. The other side 701: the plug-circuit is also connected to ground by conductors 9 9, which include the windings 0 0 of the impedance-coil 0. The earth thus forms a conductor uniting conductors 10 '9 9, whereby a permanently-closed bridge of the plug-circuit, including the battery b, is formed by the wires 9 and 10, which thus lead, in effect, to the terminals of said battery. The windings of the impedancecoil 0 are interposed in these wires, one adjacent to each of the conductors of the plugcircuit, to prevent the shunting of telephonic current through the bridge. Two relaysp and p are interposed in conductor 8 of the plug-circuit, one at each side of the point of junction therewith of the bridge-wire 9 10, so

that one of the relays is in the path of cur- 11o rent to each of the stations united through the agency of the plug-circuit. The contactpieces Z of the plugs constitute the terminals of wires 11 and 12, respectively, which lead to the free pole of a battery q. cludes a supervisory signal r, which is asso- Wire 11 inciated in the switchboard with the plug is, 7

while wire 12 includes a signal-lamp r, similarly associated with plug It. The illumination of these lamps is controlled by relays p and 19', respectively, which close shunts 13 and 14 about the lamps when the relays are excited.

The successful operation of this invention depends to some extent on the proper propor- 12 5 tioning of the resistances and electromotive forces in the different parts to each other. The sources I), d, and q of current may have 'electromotive forces of twenty, four, and

eight volts, respectively. be four-volt lamps of approximately twenty ohms resistance. The windings f and f of the cut-off relay f may be of forty and fortyfive ohms, respectively. The supervisory The lamps 6 may 0 lamps r r may be similar to the lamps e, in which case the resistance of shunts 13 and 14 may be sixteen ohms. In the normal operation of this system the removal of the subscribers telephone from its switch at a station permits the battery 6 to create current in the line, which operates the line-relay c, and thus effects the illumination of the linelamp 2. The closing of the switch-contacts of relay 0 creates current in the circuit controlled by them, which excites the magnet h, and thus determines the operation of the alarm 71. A portion of the current in the local circuit finds a path throughconductor 5, including the windings f f of the cutoff relay; but since these windings are reversely connected in the circuit the magnet of the relay remains neutral. In responseto the call indicated by the display of signal 6 the operator inserts plug into the springjack (0' of the calling-line. In this act the battery q becomes connected through wire 11 with wire 6, from which it has a path through winding f to earth directly and through winding f and a portion of Wire 4:, including the line-lamp e, to earth. The currents in the two windings now cooperate to magnetize the core of the relay, whereby the switch-contacts of the cut-off relay are separated and the connections of the line-wires 1 and 2 with earth and with the relay 0 are broken. The relay 0 becomes inert, permitting its switchcontacts to break the connection between wires 3 and 4, whereby the current from battery cl through lamp 9 is broken and the magnet h is rendered inert. The portion of current which flows from battery q through lamp 6 is insulficient to illuminate this lamp, since it has in series with it the magnet f of the cut-off relay, and both it and the winding f are shunted by the windingf of the same relay. The subscribers telephone having been removed from its switch at the substation when the operator inserted plug 70 into springjack ct, the relay 10 becomes excited by current flowing from battery b through the wind ings of the impedance-coil, and thence to the subscribers station and closes the shunt 13 about the supervisory signal 1*. Hence this signal remains dark. Having received the su bscribers order for the connection required, the operator tests the line called for by applying the tip of plug 7c to the test-ring g of the line. If the line be free for usethat is, if all the appliances associated with it be in their normal conditions,as represented in the drawing-no source of current is connected with the test-rings and no electrical change is produced in the application of the plug to the test-ring. If, however, the subscribers telephone were removed from its switch for use, the corresponding line-relay 0 would have become closed and would have connected battery d through wire 3, a portion of wire 4:, a portion of wire 5, including winding f, and wire 6 with the test-rings, and the application of the plug to the test-ring would result in a current through these wires and through a portion of conductor '7 and winding 0 of the impedance-coil to earth, whereby a distinctive test-signal would be produced inductively in the operators telephone, or, similarly, in case an operator at a distant switchboard had established connection with the line by means of a plug havin g connections similar to those of plug 70 a circuit would exist from battery q through the wire 12 to the test-rings of the line to be tested, whereby a similar test-signal would be produced in the telephone of the operator testing. Having ascertained the idle condition of the line called for, the operator thrusts plug it into the spring-jack of the line and rings the bell at the station by means of the calling-key m. The insertion of the plug in the spring-jack completes a circuit through wires 12 and 6 to the cut-oft relay, whereby that relay of the line called for becomes excited and severs the connection of the line conductors with the line-relay. Hence the latter relay remains inert and the line-lamp associated with it does not become lighted at the response of the called subscriber. The relay 1), however, remains inert until the telephone at the called station is removed from its switch, whereupon it closes the shunt 14 about the previously-lighted signal-lamp r and extinguishes that lamp.

Having thus considered the normal operation of the system, the function of the devices of the present invention in indicating the broken condition of the line-lamps may now be traced. Suppose that the lamp 6 of the line were broken or that any defect existed in the circuit through it. The removal of the station-telephone for use would effect the operation of the alarm or pilot signal t' before the operator, but would fail to illuminate lamp 6. The operator observing the display of the general signal 1' would ascertain the identity of the calling-line and would replace the broken signal-lamp of that line. Assume, on the other hand, that an operator should attempt to make connection with a line whose lamp was broken. In this case the operator would at once insert plug it into 'a springjack of the line and would call the subscriber in the usual way. Now, however, the relay 1) would be inert, the subscriber not yet having answered, and hence the supervisory lamp 1'' would be in circuit. The current through it would be less than normal, however, since the branch through winding f and lamp e to ground would be interrupted in the broken lamp, the complete branch of the circuit being that only through winding f of the cutoit relay. Hence the supervisory lamp instead of being illuminated to its full candlepower would be dimly lighted, and its dim ness would be a signal to the operator that the circuit through the line-lamp of the line with which connection had been made was defective and would enable her to locate and replace the defective lamp.

Many other systems of circuits involving incandescent lamps as signals in telephoneswitchboards have been provided. To most of these this invention may be applied with suitable modifications, which will be obvious to those familiar with telephonic appliances.

I desire to secure by Letters Patent 1. The combination with a local circuit and a switch controlling the circuit, of a lamp in the circuit and a shunt about the lamp, a spring-jack of the telephone-line and a plug therefor, a supervisory signal associated with the plug, and circuit connections closed in registering contacts of the plug and spring-j ack, adapted to bring the said supervisory signal into circuit with the shunted lamp, whereby the response of the supervisory signal is made independent of the condition of the lamp, as described.

2. The combination with a telephone-line, a line-relay responsive to currents in the line, a local circuit for the relay, and a lamp signal in the local circuit-appearing in the telephone-switchboard, of a shunt about the lamp and an alarm signal device in the circuit responsive to currentthrough the shunt, as described.

3. The combination with a group of telephone-lines, each provided with a relay responsive to current in its line, with a local circuit controlled by the relay, and with a signal-lamp in the local. circuit, of a shunt about each signal-lamp, a conductor common to all said local circuits, a low-resistance electromagnet in the said common conductor and a signal controlled by the said magnet, as described.

4. The combination with a telephone-line, of a signaling-circuit associated therewith including a source of current and divided at one point into parallel branches, a signal-lamp in one of the branches, the other branch including a resistance, and means for controlling current in the circuit to light the signal, of a second or supervisory signal-lamp and a local circuit therefor including a source of current, said local circuit being constituted in part by the parallel branches of the first-mentioned signalingcircuit and being completed in establishing connection with the telephone-line, the said supervisory signal-lamp being adapted to be lighted by a current flowing in its local circuit when both of the parallel branches are completed, as set forth.

5. The combination with a telephone-line and a lamp-signal therefor in a switchboard, of a spring-jack and plug for making connection with the line, a signal-indicating instrument associated with the plug, and local-circuit connections including the line lamp adapted to bring the said lamp into series with the said signal-indicating instrument when connection is made with the line, whereby an interruption of the circuit in the lamp maybe detected in making connection with the line, as described.

6. The combination with a telephone-line and a lamp signal therefor in a switchboard, a spring-jack for the line and a plug for making connection therewith, of a supervisory lamp associated with the plug, a local circuit for the line and a source of current included therein, said local circuit being divided into parallel branches, one of which includes the signal-lamp, a resistance-coil in the other branch, and registering switch-contacts of the plug and spring-jack adapted to bring the said supervisory lamp serially into the local circuit, as described.

7. The combination with a telephone-line, a switch at the station thereof determining the flow of current in the line and a relay re'- sponsive to such current, a cut-off relay for the line-relay, spring-jacks connect-ed with the line and plugs for use therewith, of a local-battery circuit closed in registering contact-pieces in the spring-jack and plug including the magnet of the cut-0H relay, a local circuit controlled by the line-relay, and a secondary signal therein, said local signalcircuit being connected with the circuit through the cut-off relay, the circuit connections of the windings of the relay with the said local circuits being adapted to leave the relay inert as to current circulating in the signal-circuit, as described.

8. The combination with a telephone-line, a line-relay responsive to current in the line and a cut-off relay, of a local circuit controlled by the line-relay and a secondary line-signal included therein, two serially-connected differential windings of the cut-0K relay in a shunt of the line-signal, a spring-jack for the line and a plug therefor, and a local-battery circuit closed in registering contacts of the spring-jack and plug including the said windings of the cut-off relay in-suitable direction to cause the excitement thereof by current in the circuit, as described.

9. The combination with a telephone-line, a switch determining the flow of current in the line during the use of the telephone, a linerelay and a source of current in the line at a central office, a cut-0d relay adapted to break the line-circuit in the switchboard when excited, spring-jacks for the line and connecting-plugs and plug-circuits therefor, ofaline signal-lamp and a local circuit controlled by the line-relay including said lamp, seriallyconnected differential windings of the cut-ofi relay in shunt about said lamp,a circuit closed in registering contacts of the spring-jack and plug including the windings of said cut-off relay in multiple, a supervisory signal in the portion of said local circuit terminating in the plug, and means for controlling the display of the supervisory signal, substantially as described.

10. The combination with a telephone-line extending from a substation to a central office, of a line-relay in the circuit of the line at the central office, a source of current and means at the substation for determining the flow of current in the line, a local signal-circuit controlled by said line-relay, a source of current and a line signal-lamp included in said local circuit, an alarm signal device responsive to the flow of current in said local circuit, and a shunt about the line-lamp, whereby the response of the alarm signal device is made independent of the condition of the lamp, substantially as set forth.

11. The combination with a telephone-line extending from a substation to a central office, of a relay in the line-circuit at the central oflice, a source of current and means at the substation for determining the flow of on rrent in the line, a local circuit including a source of current and an alarm device in series and having two parallel branches, one of said branches including a line signal-lamp,

and theother branch including resistance, a spring-jack for the line, a connecting-plug adapted for insertion in said spring-jack to establish connection with the line, and a local circuit including a source .of current and a supervisory signal, said local circuit being closed in registering contacts of the plug and spring-jack when connection is made With the line, a part of said local circuit being made up of the two parallel branches of the firstmentioned local circuit, as set forth.

In Witness whereof I hereunto subscribe my name this 18th day of November, A. D. 1896.

CHARLES E. SCRIBNER. Witnesses:

ELLA EDLER, DUNCAN E. WILLETT. 

